1. Field of the Invention
The invention relates to methods of preparing foamed, crosslinked low density polyethylene, and in particular to certain linear or acyclic peroxyketals useful as dual functioning crosslinking/blowing agents.
2. Prior Art
U.S. patent application Ser. No. 122,229 filed Feb. 19, 1980, now U.S. Pat. No. 4,276,247 discloses certain cyclic peroxyketals for dual purpose use in crosslinking and foaming of polyethylene.
U.S. Pat. Nos. 4,130,700 and 4,052,543 and British Pat. No. 1,047,830 disclose the use of linear peroxyketals, such as n-butyl 4,4-bis(t-butyl peroxy)valerate, as crosslinking agents for various polymers including ethylene-propylene rubber and low density polyethylene. Ethyl 3,3-bis(t-butyl peroxy)butyrate was used in ethylene-propylene rubber (Example 9).
U.S. Pat. Nos. 2,749,519, 2,756,035 and 2,757,427 disclose the use of such linear peroxyketals in curing unsaturated polyesters, styrene, chlorinated polyethylene and/or styrene-butadiene rubber.